Hi,
On the DAR route, TK use their newer 737-900ER which have the skyinterior. The Y is 777 style in 3-3 with same IFE sans wifi. In J, the seats are not lie flat but more of regional business class in 2-2 with 35in pitch according to seatguru. I flew the same aircraft NBO-IST last year and it was quite nice (I had an exit row seat). Only thing with TK is the timings are a bit weird but it does avoid the terrible DAR traffic. Food was good and service was usual TK service.
Hope this helps